1. Field of the Invention
The present invention relates to an improved system for mounting a tool element subassembly on the output spindle of a power tool, and more particularly, to an annular composite washer assembly received over the tool spindle of a heavy-duty portable grinder and disposed axially between the collar portion of an abrasive disc subassembly and an annular shoulder formed on the spindle, thereby providing a "soft" mounting system for preventing the abrasive disc subassembly from locking or jamming against the shoulder on the spindle.
2. Description of the Prior Art
The abrasive disc subassembly used on a heavy-duty portable grinder consists of an abrasive disc carried by an internally-threaded collar. The collar is mounted on the externally-threaded spindle of the grinder. As the motor in the grinder is energized, the collar self-threads on to the spindle and bears against an annular shoulder formed on the spindle. While thus securely mounting the abrasive disc subassembly to the spindle, it is often quite difficult to remove the subassembly from the spindle. The collar tends to lock or jam against the shoulder on the spindle, especially as the grinder is used repeatedly; and the situation is aggravating on heavy construction jobs, maintenance operations or the like, where the abrasive disc subassembly quickly becomes worn and must be replaced frequently.
In an apparent effort to correct this problem, others in the art have resorted to a composite assembly, which is placed over the spindle and is disposed axially between the annular shoulder on the spindle and the collar on the abrasive disc subassembly. The composite assembly is a "sandwich" and consists of a pair of metal washers adhesively bonded to a rubber or plastic washer therebetween. While perhaps alleviating the problem initially, this composite assembly does not work over an extended period of time, especially in the severe environment often encountered in the use of a heavy-duty portable grinder. More specifically, the washers may not be properly alined coaxially with one another, tolerance accumulations in the overall assembly are not readily compensated, and the plastic or rubber tends to rapidly extrude from the sandwiched assembly after a few uses. This destroys the utility of the assembly for the purposes intended.
Moreover, in the general art relating to various means for reducing vibration and noise during operation of a power tool, a number of designs and constructions have been disclosed. For example, in U.S. Letters Pat. No. 4,067,184, a fabricated washer assembly has been disclosed consisting of a pair of plastic washers with a soft rubber washer therebetween. Each of the plastic washers has a pair of projections received through holes in the intermediate rubber washer and received in corresponding holes formed in the other washer. The purpose of this construction is to reduce vibration and noise. This result is altogether different from the primary objective of the present invention.